As much as a wagon can carry. (Often used hyperbolically.)

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1721.  Cibber, Refusal, I. 1. Well, how goes Mississippi, man? What do they bring their money by waggon loads to market still?

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1728.  Young, Love Fame, I. 87. Imperious some a classic fame demand, For heaping up with a laborious hand, A waggon-load of meanings for one word.

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1807.  Farmer’s Mag., Nov., 471. A waggon-load [of wheat] is 12 or 14 barrels; each barrel 196 lib. weight.

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1837.  Dickens, Pickw., v. He wouldn’t shy if he was to meet a vaggin-load of monkeys with their tails burnt off.

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1855.  Macaulay, Hist. Eng., xvii. IV. 66. He carries with him … a waggonload of plate.

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1913.  J. G. Frazer, Golden Bough, VII. Balder, I. iv. 118. The butchers were rewarded with a waggon-load of wine.

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